Intermittent texturized yarn and false-twist apparatus and process for producing the same

ABSTRACT

An intermittently texturized novelty yarn and improvements in the conventional false-twist texturizing process and apparatus for making the yarn. The conventional heater is replaced, preferably, with a fluid jet equipped for scheduled fluid flow. A fluid heating medium preferably in the form of superheated steam is intermittently passed through the jet preferably at sonic velocity, thereby heat-setting the false-twist in successive spaced portions of the yarn contacted by the steam. The intervening portions of the yarn which have not been subjected to heat-setting lose their false-twist as they pass out of the texturizing zone.

United States Patent [191 London, Jr.

[ INTERMITTENT TEXTURIZED YARN AND FALSE-TWIST APPARATUS AND PROCESS FOR PRODUCING THE SAME [75] Inventor: Joe F. London, Jr., Greensboro,

[73] Assignee: Burlington Industries, Inc.,

Greensboro, NC,

[22] Filed: Sept. 25, 1972 [21] Appl. No.: 291,586

[52] U.S. Cl 57/34 HS, 28/l.2, 28/72.12, 57/157 TS [51] Int. Cl D02g l/02, D02g 1/16 [58] Field of Search 57/34 HS, 140 J, 157 TS; 28/l.2, 72.12, 61, 62; 251/345 [56] References Cited UNITED STATES PATENTS 184,573 11/1876 Becker 251/345 X 453,109 5/1891 Dreisorner 251/345 X 764,322 7/1904 Wiegand 251/345 X 1,672,258 6/1928 Hippenmeyer 251/345 X 2,332,114 10/1943 Robb 251/345 X 2,952,116 9/1960 Berrlson 57/157 TS 2,968,909 1/1961 Camer et a1 57/157 TS 3,136,111 6/1064 3,263,298 8/1966 3,686,845 8/1972 Okada et a1. 57/34 HS Primary Examiner-John W. Huckert Assistant Examiner-Charles Gorenstein Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7 ABSTRACT An intermittently texturized novelty yarn and improvements in the conventional false-twist texturizing process and apparatus for making the yarn. The conventional heater is replaced, preferably, with a fluid jet equipped for scheduled fluid flow. A fluid heating medium preferably in the form of superheated steam is intermittently passed through the jet preferably at sonic velocity, thereby heat-setting the false-twist in successive spaced portions of the yarn contacted by the steam. The intervening portions of the yarn which have not been subjected to heat-setting lose their false-twist as they pass out of the texturizing zone.

10 Claims, 8 Drawing Figures PATENTEB W1 91974 3, 848 ,404

SHEET 4 BF 5 INTERMITTENT TEXTURIZED YARN AND FALSE-TWIST APPARATUS AND PROCESS FOR PRODUCING THE SAME This invention relates to texturizing yarn and more particularly to improvements in conventional falsetwist texturizing apparatus and to a method for producing a novel yarn having alternate textured and untextured portions.

The texturizing of standard conventional filament yarn was initially proposed as a means for producing novel yarns which would offer a wider latitude in fabric design and styling. Several different texturizing processes have been developed, each of which produces texturized yarns of recognized different characteristics. Probably the most popular of these yarns are those which are produced by conventional false-twist texturizing. False-twist texturized yarns are now in such widespread use as to become commonplace, their variety and style potential in fabric design having been substantially exhausted. Throughout the period of acceptance of false-twist textured yarn, there have been many attempts to produce yarns which would provide still wider latitude in fabric design and styling while retaining all of the desirable characteristics of conventionally false-twist textured yarn. Particularly sought for has been an economical false-twistingmethod for producing a yarn alternating textured and untextured in short or variable intervals along its length. This has been attempted by such means as varying the spindle speed, temperature, or overfeed, removing the yarn periodically from the heater, or adding chemicals to the yarn before texturing. None of these attempts has been significantly successful. This is primarily either because such variants do not take effect fast enough to yield sharp changes from an untextured to a textured state, or because one or both of the successive textured or untextured zones are excessively long. In order for a process to be useful, the point of change of textured to untextured and vice versa should be easily controlled and either abrupt or over a short length of yarn to give an appearance suitable for design work. Other approaches for producing yarn of this type involve pretreatment and post-treatment of the yarn in conjunction with conventional texturizing processes. An example of a disclosure of this type is contained in Holton US. Pat. No. 3,263,298 dated Aug. 2, I966, wherein the feed yarn is not the conventional commercially available yarn of the present invention, but a specially prepared thick-thin yarn. The need remains for a method for creating a freely variable intermittently textured-untextured yarn from a conventional yarn.

It is accordingly an object of the present invention to provide a process for producing false-twist textured yarn which possesses lengths of variation in texture all the way from completely texturized to completely untexturized, which lengths provide the necessary abruptness in change and controlled dimension to give an appearance suitable for design work. This objective is accomplished in accordance with the principles of the present invention by providing an improved intermit-- tent heating procedure in a conventional false-twist texturizing process, thus enabling the production of such novel yarn from conventional filament yarn without the necessity of any pretreatment or subsequent treatment. Specifically, the improved procedures of the present invention contemplate providing a region of closely adjacent surrounding peripheral confinement along a predetermined short longitudinal extent of the yarn continuously moving between the upstream position of restraint and the twisting position in a conventional false-twist texturizing process and intermittently passing a fluid heating medium, such as superheated steam, through the confinement region at a temperature and velocity sufficient to heat-set the false twist in successive spaced portions of the yarn contacted by the heating medium, while permitting the remaining portions of the yarn to pass out of the texturizing zone with the false twist imparted thereto while moving therethrough removed without being heat-set.

Another object of the present invention is the provision of an apparatus having an improved intermittently operable heating means for carrying out the procedure noted above.

Still another object of the present invention is the provision of novel variably texturized yarns made in accordance'with the principles of the present invention.

Another object of the present invention is the provision of novel fabrics made from the yarn produced in accordance with the present process and apparatus.

These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.

The invention may best be understood with reference to the accompanying drawings wherein illustrative embodiments are shown.

In the drawings:

FIG. 1 is a generally schematic view illustrating one embodiment of an apparatus constructed in accordance with the principles of the present invention for practicing the method of the present invention;

FIG. 2 is a fragmentary view similar to FIG. I illustrating a modified form of apparatus in which the intermittent actuation of the heating mechanism is a randomizing device;

FIG. 3 is a view similar to FIG. 2 illustrating still another embodiment of the improved apparatus of the present invention;

FIG. 4 is a vertical sectional view of the apparatus shown in FIG. 3;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4;

FIG. 6 is a photograph of one embodiment of a fabric according to the principles of the present invention produced on a conventional double-knit machine, the scale of the photograph being shown in the Figure;

FIG. 7 is a microscopic photograph of a portion shown in FIG. 6, the scale being indicated in the Figure; and

FIG. 8 is a photograph of another embodiment of the fabric according to the principles of the present invent i on produced on a conventional loom, the scale of the photograph being shown in the Figure.

'Referring now more particularly to the drawings, there is shown in FIG. 1 thereof an apparatus embodying the improvements of the present invention for carrying out the improved process in accordance with the principles enunciated above. As shown, a supply of thermoplastic yarn in the form of a yarn package 10 is provided from which yarn 12 is drawn, as by a feed roll mechanism 14, in the form of a set of nip rolls or the like. The nip rolls 14 serve to continuously feed the yarn l2'into a texturizing zone, indicated at 16, from which the yarn is continuously drawn by a draw roll mechanism 18, in the form of a set of nip rolls or the like. The yarn 12 passing through the texturizing zone 16 moves past a false-twisting device, schematically indicated at 20, at a position intermediate to the ends thereof so as to impart and maintain a twist in one direction, which twist extends upstream to the upstream nip rolls 14. The above component elements of the apparatus are preferably of any conventional construction of the type embodied in conventional false-twist texturizing apparatus.

The present invention is more particularly concerned with improvements in the apparatus and procedure for intermittently heat-setting discrete incremental lengths of the twisted yarn as it passes through the texturizing zone 16. The improved apparatus includes a fluid heating medium applying device, generally indicated at 22, for confining a fluid heating medium in closely adjacent surrounding relation along a predetermined length of the yarn l2 continuously moving between the upstream nip rolls 14 and the false-twisting device 20, a device, generally indicated at 24, movable between opened and closed positions for intermittently communicating a fluid heating medium to the device 22, and a control mechanism, generally indicated at 26, for effecting successive movements of the device 24 into the opened and closed positions thereof.

It will be understood that after the yarn 12 passes from the downstream nip rolls 18 out of the texturizing zone, it may be subjected to further subsequent procedures. FIG. 1, however, simply illustrates the subsequent forming of a package 28 of the intermittently texturized yarn, as by a take-up roll 30.

The device 22, which is shown schematically in FIG. 1 and in detail in FIG. 4, is preferably constructed in accordance with the disclosure set forth in commonlyassigned Flanders application, Ser. No. 291,585 filed concurrently herewith, which disclosure is hereby incorporated by reference into the present disclosure. With reference to FIG. 4,it will be noted that the device 22 includes a plenum chamber 32 having an inlet opening 34 formed in one side wall thereof. Disposed in communication with the plenum chamber 32 is a flow confining member 36 having a converging nozzle 38 formed in the end thereof which communicates with the plenum chamber. The converging nozzle is formed by an interior frustoconical surface which communicates with a throat 40 formed by an interior cylindrical surface. The throat 40 extends longitudinally through the member 36 from the nozzle 38 to the opposite free end thereof.

Mounted in the wall of the plenum chamber 32 opposed to the wall thereof within which the flow confining member 36 extends, is a yarn receiving member 42 having an interior passage 44 extending longitudinally therethrough, formed by a cylindrical surface, the axis of which is aligned with the axis of the cylindrical surface forming the throat 40.

As best shown in FIG. I, the device 22 is positioned within the texturizing zone 16 between the upstream nip rolls l4 and the false-twisting device so that a predetermined longitudinal extent of theyarn co ntiniF ously moving therein will pass through the longitudinally aligned passage 44 and throat 40 provided by the device. The passage 44 is smaller than the throat 40 so as to cause a fluid heating medium communicated with the inlet opening 36 to flow from the plenum chamber 32 through the converging nozzle 38 and outwardly to the atmosphere through the throat 40. While the device 22 may be oriented in either direction with respect to the direction of movement of the yarn 12 through the texturizing zone 16, as shown in FIG. 1, it is preferable to dispose the device 22 in a position such that the flow of fluid heating medium through the throat 40 is in the same direction as the movement of the yarn 12 through the texturizing zone 16.

The device 24 may be of any conventional construction of the type adapted to be moved into opened and closed positions for intermittently communicating a source of fluid heating medium to the device 22. In the embodiment shown in FIG. 1, the device takes the form of a conventional valve assembly. The valve assembly is schematically illustrated in FIG. 1 and includes the usual conventional valve member mounted for reciprocatory movement between opened and closed positions with respect to a valve seat positioned intermediate the inlet and outlet ends of the valve body. The inlet end of the valve assembly is communicated with the source of fluid heating medium which preferably is a source of superheated steam (not shown). FIG. 1 does schematically illustrate a series of superheaters 46 connected between the steam source and the inlet of the valve assembly 24 for controlling the superheated temperature of the steam. It will be noted that the outlet of the valve mechanism 24 is closely communicated with the inlet opening 34 of the plenum chamber 32.

The mechanism 26 in the preferred embodiment shown in FIG. 1 includes a conventional solenoidvalve-actuating assembly 48 which, asschematically illustrated, forms an integral part of the conventional valve assembly 24. The solenoid assembly 48 is connected with an energizing circuit which includes an onoff switch 50, of any conventional construction, positioned so as to be cycled by a cam 52 or the like fixed to the shaft of one of the nip rolls 14.

To exemplify the practice of the present method by the operation of the improved apparatus described above, a flow confining member 36 having a throat 40 approximately 3 inches long and 0.083 inches in diameter (member 44 being 0.021 inches in diameter), was used in processing multifilament polyester feed yarn 12 (regular, drawn, ISO-denier Dacron type 56). In the operation, which proceeded at a rate of approximately yards per minute, the following conditions prevailed. The steam source had a temperature of 470F and a pressure of 55 psig at the exit of the superheaters 46. The rotational speed of the nip rolls 14 in relation to the rotational speed of the nip rolls 18 was a l percent underfeed. The false-twisting device 20 was operated at a speed sufficient to impart 60 turns per inch to the yarn. The mechanism 26 was operated at a frequency of 400 even cycles per minute.

At these conditions, an intermittently texturized yarn was produced which had a repeating pattern every 9 inches. Within this 9-inch length, 1% inches were untexturized, 3% inches were partly texturized, and 4 inches were fully texturized. The partly texturized yarn was located on both sides of the fully texturized lengths. The longer of these partly texturized portions, resulting from the lag time in fully emptying or cooling the steam in device 22, was located on the upstream end of the fully texturized portion. The shorter partly texturized portion, the result of the lag in fully opening the inlet valve and bringing the temperature up to full texturizing level, was located at the downstream end of the fully texturized length.

The yarn produced in accordance with the above was used as the feed yarn in an l8-cut 24-feed Mayor double-knit machine to knit a fabric which was then dyed a medium shade of blue and photographed in blackand-white. FIG. 6, taken without magnification, shows the untextured sections of yarn as dark lines in the fabric, most of the fabric being textured and lightercolored. FIG. 7, a microscopic enlargement centered along one of the dark lines, shows a line to be comprised of loops of untextured yarn, its surroundings being comprised of bulked yarns.

The photographs thus conform that the intermittently textured yarn imparts variation of both texture and dyeability to fabricsmade of it, these variations being valuable in many end uses. The dyeability variation accents the structural difference, the combination of effects creating a very desirable and interesting product.

The above description presents only one example of the versatility of the invention. The capability of setting yarns in lengths of the order of 3 to 6 inches or below, compared with 40 or more inches achieved on most texturizing machines, is demonstrated. The capacity for creating an even repeating pattern is shown, but it should be recognized that many uses will require a greater variance in the textured and untextured lengths. The dimensions of the fluid jet, here shown as 3 inches long, are not critical, longer or shorter, larger or smaller in bore jets being readily adaptable for creation of special effects, increased production rates, and the like. Interesting novel fabric designs may be created from the yarns of the invention by means other than knitting, such as weaving.

In order to have more variability in the yarn and to prevent an unwanted lining up or patterning in fabric, some form of randomization is usually preferably added to the process. Such randomization can be provided by any of the known randomizing devices heretofore utilized in producing conventional slub yarns. A particularly desirable randomizing device is disclosed in the commonly-assigned Pugh application Ser. No. 158,961, filed July 1, 1971, entiteld Control Mechanism for Producing Random-Like Effects on Textile Materials. FlG. 2 schematically illustrates the use of a device of this type, indicated by the numeral 54, the electrical output of the device providing the circuitry to the solenoid assembly 48 associated with the valve mechanism 24. With the use of such a device, any desirable pseudo-random pattern can be secured in accordance with the teachings contained in the aforesaid Pugh application disclosure, which is hereby incorporated by reference into the present disclosure.

While a reciprocating valve mechanism can be readily used in the present apparatus for interrupting the communication of the fluid heating medium source with the confining device 22, such devices may provide only a limited operative life when operated at relatively high frequencies at relatively high feed rates of the overall apparatus. For example, lr million cycles within a 24-hour-day operation might well reach the normal wear life of conventional valves in a very short time. Consequently, in order to permit higher operating rates and still maintain high frequency cycles in the device 24, it is desirable to utilize a device of this type which is moved into opened and closed positions by a rotary movement rather than a reciprocating movement. An example of such a device is illustrated in FIGS. 4 and 5 and designated generally by the numeral 56. The device 56 includes a valve body 58 which, as shown, is of tubular configuration having a discharge end connected with the inlet opening 34 of the device 22 and an inlet end communicating with the source of superheated steam. Mounted within the central portion of the tubular structure 58 is a transverse wall 60 which completely blocks the interior of the tubular structure. On opposite sides of the wall there are provided a pair of radial openings 62 in the wall of the tubular structure providing a flow path to and from the exterior central portion of the tubular structure.

Rotatably mounted on the tubular structure 58, as by ball bearings 64 or the like, is a valve block member 66. The valve member is provided with a longitudinal bore 68 of a size to closely embrace the exterior periphery of the tubular structure 58. Formed in the central portion of the bore 68 adjacent the openings 62 is an arcuately segmental slot 80, which, when the openings 62 are registered therewith provides a confined flow path for the steam from the downstream opening 62 to the upstream openings 62. Likewise, it will be understood that when the openings 62 are disposed within the surface of the bore 68 the flow path through the tubular structure is closed. With this construction the rotation of the valve member 68 will serve to intermittently communicate the source of superheated steam with the device 22.

Any suitable means may be provided for effecting rotational movement of the valve member 66, as, for example, an electric motor 70 rotatably drivingly connected therewith as by a belt and pulley 72. It will be understood than an arrangement of this type will permit high speed operation over an extended period of time, because of the greater normal wear life which is attributable to rotating mechanisms as distinguished from reciprocating mechanisms such as the conventional reciprocating valve assembly 24. It will also be understood that various methods of randomizing the rotational movement may likewise be provided, such as the use of a variable-speed motor and circuitry for varying the speed thereof, as by a randomizer or the like.

It will be further understood that additional stabilizing or annealing action such as double-heater falsetwisting, autoclaving, package dyeing, or other posttreatments commonly applied to false-twisted yarns and fabrics may if desired be applied to the intermittently textured yarns of the invention. The invention may be used in conjunction with any of the conventional false-twisting methods, including spindlette, friction, and other methods using false-twist principles. The products of the invention, unless the textured portions are deliberately kept too low, inherently have the stretch characteristics of other false-twist textured yarns and fabrics. Although specifically applied herein only to polyester yarns, the invention is also useful with other yarns which can be texturized by false-twisting.

The following examples further illustrate the utilization of the concepts and procedures of the invention.

EXAMPLE 1 Ten runs of regular, drawn, multifilament Type 56 Dacron polyester yarn (150/34) were textured on a spindle-type false-twister at 100 yd/min, 62 tpi, and 1 percent underfeed. The yars were heat-set in a 3-inch jet with steam at 55 psig and superheated to 470P, according to schedules detailed below.

The flow of steam to the jet were interrupted by an air-operated on-off steam valve, actuated by a solenoid air valve controlled by a randomizer as described in the aforesaid Pugh application, wherein the means for establishing widely varied pseudo-random patterns of action on the yarn are described in detail. Each setting of the randomizer produced a complex pattern of textured and untextured lengths of yarn. In this manner the lengths of either or both the textured and untextured portions of yarn were varied in 14 discrete steps between pre-set maxima and minima.

Table 1 summarizes the results of applying ten different on-off patterns to the ten runs of yarns, Samples A-J. Only the calculated maximum and minimum yarn lengths are tabulated, these being derived from the speed of the yarn and the open-closed times of the randomizer. ln Sample A, for example, the minimum length of untextured yarn was about 5 inches, while the maximum was about inches. The minimum length of textured yarn was 180 inches and the maximum was 360 inches. Only a calculated 2.7 percent of the yarn remained untextured. ln Sample D, the minumum textured length was only 1% inches while the maximum untextured length was 50 inches, producing a yarn with 37.5 percent untextured length. Sample G was one with a non-random pattern of untextured yarn, all of its untextured lengths being 8 inches, with a great predominance of widely varied textured lengths and only 1 percent of untextured length.

" Table 1 8 knitted into a single-jersey fabric and dye dI'The fabric was similar to one produced from conventional set polyester but was more attractive because of the areas which dyed dark and had no crimp.

EXAMPLE 3 EXAMPLE 4 Another run of the Sample H yarn of Example 1 was package-dyed in a conventional package-dye machine and then converted to a single-jersey fabric. The darkdyed untextured areas were distinctly evident and the aesthetic effect of the fabric was attractive.

EXAMPLE 5 A rotary valve as hereinbefore described was modilied to allow for steam in the line between the valve and jet to escape to the atmosphere when the incoming line was closed. This decreased the length of time required for the steam to empty out of the jet, thus making for a rapid change from textured to untextured. With this valve, rotated at a constant 150 rpm, the yarn of Example 1 was texturized under the same conditions to produce a regularly repeating pattern of 24 inches, made up of about 16 inches textured and eight inches untex- Pseudo-Random lntermittently Textured Polyester Untexturcd length, 14 discrete lcngths Textured length,

14 discrete lengths Eac'hbf the 10 arafivafim'ataiaa 'double ldii t fabric on an l8-cut 24-feed double-knit machine and the fabrics were dyed. The untextured areas, approximately the same percentage ofthe fabric as shown in the yarn table, dyed darker. The resulting fabric patterns, differing in both surface struture and color shade, were pleasingly varied and attractive to the eye.

EXAMPLE 2 A sample of yarn textured like Sample H of Example 1 was 25 percent overfed into a conventional second heater at 410F and then wound onto a package in a conventional manner. This step was equivalent to producing a double-heater yarn or set yarn. The yarn was turedl A uniform pattern of light and dark areas emerged when the yarn was knitted to a single-jersey fabric and dyed. This was due to the absence of crimp and the darker shading in the unset areas.

EXAMPLE 6 Polyester yarn made according to Sample 0 of Example 1 was woven as filling in a 40-denier nylon warp to see the effect the yarn would produce in a woven fabric. The fabric was dyed dark blue. 1n the resulting pattern the textured areas were darker looking than the untextured, the reverse of the effect with the knitted samples. The fabric had bright flashes at random in the filling direction, caused by the greater luster of the untextured portions of the filling yarn. The fabric is pictured in FIG. 8.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

l. A method of texturizing thermoplastic yarn which comprises the steps of continuously feeding a substantially uniformly continuous yarn into and out of a texturizing zone, maintaining a false twist in the yarn within said texturizing zone by continuously imparting a twist to the yarn at a twisting position spaced downstream from an upstream position of restraint, providing a region of closely adjacent surrounding peripheral confinement along a predetermined short longitudinal extent of the yarn continuously moving between said upstream position of restraint and said twisting position, and intermittently passing superheated steam through said confinement region at a sonic velocity so as to heat-set the false twist in successive spaced portions of the yarn contacted by said superheated steam while permitting the remaining portions of the yarn to pass out of said texturizing zone with the false twist imparted thereto while moving therethrough removed without being heat set.

2. A method as defined in claim 1 wherein at least some of said portions are of a longitudinal extent less than approximately 7 inches.

3. A method as defined in claim 1 wherein said portions are of a random longitudinal extent throughout.

4. A method as defined in claim 3 wherein at least some of said portions are of a longitudinal extent less than approximately 7 inches.

5. A method as defined in claim 1 wherein said portions are of predetermined repetitive longitudinal extent throughout.

6. A yarn made in accordance with the method of claim 1.

7. In an apparatus for false twist texturizing thermoplastic yarn including spaced feed roll means defining a texturizing zone therebetween for continuously feeding yarn into and out of said texturizing zone, and a false twist mechanism disposed at a twisting position within said texturizing zone for imparting and maintaining a false twist in the yarn within said texturizing zone which extends upstream from said twisting position to a spaced position of twist restraint, the improvement in combination therewith which comprises a housing structure having longitudinally extending surface means of relatively short length of a size and shape to receive the yarn therethrough in closely surrounding relation thereto, an inlet opening spaced from said surface means for communication with a source of heated fluid under pressure, means defining a flow path for the heated fluid from said inlet opening to one end of said surface means, valve means within said flow path movable into opened and closed positions respectively permitting a source of heated fluid under pressure communicated with said inlet opening to flow rapidly through said surface means from said one end to the other end thereof in heat transfer relation with a yarn moving therethrough and preventing such heated fluid from flowing through said surface means, and means for effecting successive movements of said valve means into said opened and closed positions so as to heat set the false twist in spaced portions of the yarn corresponding to the portions to which the heated fluid flows in heat transfer relation therewith when said valve means is in said opened position.

8. The combination as defined in claim 1 wherein said valve means comprises a valve member mounted for reciprocating movement between said opened and closed positions, and said movement effecting means comprises solenoid means connected with said valve member to move the same and means for energizing and de-energizing said solenoid means.

9. The combination as defined in claim 7 wherein said valve means comprises a valve member mounted for rotary movement into said opened and closed positions and said movement effecting means comprises means for rotating said valve member.

10. The combination as defined in claim 7 wherein said surface means is of a longitudinal extent less than approximately 7 inches. 

1. A method of texturizing thermoplastic yarn which comprises the steps of continuously feeding a substantially uniformly continuous yarn into and out of a texturizing zone, maintaining a false twist in the yarn within said texturizing zone by continuously imparting a twist to the yarn at a twisting position spaced downstream from an upstream position of restraint, providing a region of closely adjacent surrounding peripheral confinement along a predetermined short longitudinal extent of the yarn continuously moving between said upstream position of restraint and said twisting position, and intermittently passing superheated steam through said confinement region at a sonic velocity so as to heat-set the false twist in successive spaced portions of the yarn contacted by said superheated steam while permitting the remaining portions of the yarn to pass out of said texturizing zone with the false twist imparted thereto while moving therethrough removed without being heat set.
 2. A method as defined in claim 1 wherein at least some of said portions are of a longitudinal extent less than approximately 7 inches.
 3. A method as defined in claim 1 wherein said portions are of a random longitudinal extent throughout.
 4. A method as defined in claim 3 wherein at least some of said portions are of a longitudinal extent less than approximately 7 inches.
 5. A method as defined in claim 1 wherein said portions are of predetermined repetitive longitudinal extent throughout.
 6. A yarn made in accordance with the method of claim
 1. 7. In an apparatus for false twist texturizing thermoplastic yarn including spaced feed roll means defining a texturizing zone therebetween for continuously feeding yarn into and out of said texturizing zone, and a false twist mechanism disposed at a twisting position within said texturizing zone for imparting and maintaining a false twist in the yarn within said texturizing zone which extends upstream from said twisting position to a spaced position of twist restraint, the improvement in combination therewith which comprises a housing structure having longitudinally extending surface means of relatively short length of a size and shape to receive the yarn therethrough in closely surrounding relation thereto, an inlet opening spaced from said surface means for communication with a source of heated fluid under pressure, means defining a flow path for the heated fluid from said inlet opening to one end of said surface means, valve means within said flow path movable into opened and closed positions respectively permitting a source of heated fluid under pressure communicated with said inlet opening to flow rapidly through said surface means from said one end to the other end thereof in heat transfer relation with a yarn moving therethrough and preventing such heated fluid from flowing through said surface means, and means for effecting successive movements of said valve means into said opened and closed positions so as to heat set the false twist in spaced portions of the yarn corresponding to the portions to which the heated fluid flows in heat transfer relation therewith when said valve means is in said opened position.
 8. The combination as defined in claim 1 wherein said valve means comprises a valve member mounted for reciprocating movement between said opened and closed positions, and said movement effecting means comprises solenoid means connected with said valve member to move the same and means for energizing and de-energizing said solenoid means.
 9. The combination aS defined in claim 7 wherein said valve means comprises a valve member mounted for rotary movement into said opened and closed positions and said movement effecting means comprises means for rotating said valve member.
 10. The combination as defined in claim 7 wherein said surface means is of a longitudinal extent less than approximately 7 inches. 